In recent years, in a suspension arm mounted on a vehicle such as an automobile, one piece of steel plate is often press-formed to form the suspension arm in order to achieve light weight and cost reduction of the vehicle.
Under such circumstances, Patent Document 1 relates to a suspension arm of an automobile, and discloses a configuration in which a notched portion is formed in a vertical wall portion connecting between a front attachment portion and a rear attachment portion, in order to prevent stress concentration on a collar welded portion without increasing the number of components and the cost.